Sawflies are primitive wasps that do not sting. There are several families including pamphilids. Most of them are herbivores and while some feed on deciduous trees, most of the species in Washington feed on conifers. The larvae are caterpillar-like and can be rather large, up to an inch or more in length. They are webspinners and when finally noticed, one sees a sizeable "nest" of webbing, frass (small chunks of excrement), and chewed dead needles in the tree canopy. Larval feeding on needles can cause localized defoliation, but they are rarely a significant problem.